This chart reflects the results of the latest Economist / YouGov Poll -- done between August 17th and 20th of a national sample of 1,111 registered voters, with a margin of error of 3 points.
It shows that currently Donald Trump trails a generic Democratic candidate by 8 points among registered voters. This is primarily due to the distaste of women voters for Trump and his policies. While he leads among men by 5 points, he has a huge 13 point deficit among women -- and women outvote men in our national elections.
Trump may actually be waking up to his problem with women voters. His campaign is sending women (like Kellyanne Conway and Jan Brewer) to battleground states to try and convince women they are wrong, and should support Trump in the 2020 election.
I doubt they will have much success. On the same day this effort was announced, Trump doubled down on some things that bother women voters. He announced an executive order that would allow him to keep immigrants (including children) in detention facilities for an unlimited time. He said any Jewish person voting Democratic was being disloyal. He flip-flopped on background checks. and he continued his hate speech on Democratic women of color.
As long as he continues this kind of policies, hate speech, and support for white supremacists, he not going to win over women voters.